I've been giving this some more thought. I am through chapter 6 so far, so I believe I may have covered the relevant portions to follow up with you.

How does one discern the difference between obsession (perhaps with a hefty side of old fashioned guilt) and the very real possibility that they are perhaps simply ignoring a call to vocational ministry? I can see this both ways. What if the call has never materialized in a concrete fashion? What if it's been something of a steady pull for a couple of decades?

As a side question, is the Saddleback SHAPE test something that is readily available?

“How does one discern the difference between obsession...”: I’d start by asking the Holy Spirit to help evaluate your heart: Are you living in obedience to God? Do you believe that obeying him will lead to joy (chapter 11)? Beware over-analyzing yourself. Simply, do you desire to obey him, by his grace?

Then ask the Spirit to help you evaluate this call to ministry: Does it feel like an obligation and burden or an anticipation and joy? As I said in the book, I find that God usually leads the obedient heart through joy. Also, as you look at vocational ministry, does it make sense of how God has directed your life over the past many years?

“What if the call has never materialized in a concrete fashion?” First, sometimes fulfilling God’s call can look very different than what you imagined. Also, you may be in an in-between place right now, or already where he wants you. All you can do is obey in whatever way you can, right where you are now (BTW: I’m in an in-between spot now, with little clear direction, so all I can do is be as faithful as possible here.)

That said, if you feel like God is pulling you to vocational ministry, find ways to prepare even now, as you wait: Read books that may help you, pray and love others as if you were in vocational ministry, and serve in areas that bring you joy.

I hope this was helpful. Let me know if you need any clarification.

Oh, check out this website for SHAPE (it's just a worksheet, but should be helpful): http://www.fbcbristol.org/docs/SHAPE_Inventory.pdf